[Patches] [ python-Patches-1498370 ] Improve itertools.starmap

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Patches item #1498370, was opened at 2006-06-01 03:41
Message generated for change (Comment added) made by anthonybaxter
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Category: Modules
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Collin Winter (collinwinter)
Assigned to: Anthony Baxter (anthonybaxter)
Summary: Improve itertools.starmap

Initial Comment:
As it currently stands, the iterator argument to
itertools.starmap() must yield tuples, even those any
iterable can be *-expanded in function calls. The
attached patch changes starmap()'s behaviour (as well
as docs and tests) to allow the provided iterator to
return any iterable object.

The patch is against r46582.

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>Comment By: Anthony Baxter (anthonybaxter)
Date: 2006-07-25 17:20

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Hm. Making the code agree with the docs is a good plan.
Please make sure to include a very clear NEWS item.


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Comment By: Jack Diederich (jackdied)
Date: 2006-07-18 13:42

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Raymond's intuition for bare metal is correct.  My suggested
simplifaction slowed down the tuple case by most of a
percent (I benchmarked it but left it out of the comment). 
Preternatural, I tell you.

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Comment By: Raymond Hettinger (rhettinger)
Date: 2006-07-17 11:00

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Since starmap() is documented to behave like "yield 
function(*iterable.next())", I think this fixup can be 
considered a bugfix.  If Anthony is okay with this, it 
should into Py2.5.

While Jack's suggested modification leads to a 
conceptually simpler patch, I prefer an alternate version 
that only calls PySequence_Tuple() if PyTuple_CheckExact() 
fails.  That will make sure that we don't slow down the 
most common case.

Also, I prefer slightly different updates to the docs and 
test suite.  If Anthony approves for inclusion in Py2.5, I 
will upload my own version of a patch to starmap().

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Comment By: Collin Winter (collinwinter)
Date: 2006-06-27 19:22

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I've updated the patch per jackdied's suggestion, plus
improved the test suite a bit.

The patch is now against r47103.

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Comment By: Jack Diederich (jackdied)
Date: 2006-06-10 06:13

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The patch can be simplified by always calling
PySequence_Tuple() and doing the decref instead of special
casing tuples.  If you pass PySequence_Tuple() a tuple it
will  incref it and hand it back to you.


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Comment By: George Yoshida (quiver)
Date: 2006-06-01 11:36

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